Tension control mechanism



July 19, 1966 G F, WASSON 3,261,191

TENS ION CONTROL MECHANI SM Filed Aug. 6, 1963 2 Sheets-Sheet l July 19, 1966 G. F. wAssoN 3,261,191

TENS ION CONTROL ME CHANI SM Filed A11g- 6, 1963 2 Sheets-Sheet 2 wmp/EQ,

United States Patent C) 3,261,191 TENSION CONTRGL MECHANISM George F. Wasson, Bethel Park, Pa., assignor to Voss Engineering Company, Pittsburgh, Pa., a corporation of Pennsylvania Filed Aug. 6, 1963, Ser. No. 360,319 7 Claims. (Cl. 72--9) This invention relates in general to a tension control and more particularly to a tension control system for use with a metallic strip material leveler.

Prenished metallic strip material is normally stored in coils. In handling such strip material for further processing, the strip of material is usually unwound from the coil, processed and then rewound in coil form. For eX- ample, strip material is unwound from a coil and excess material is removed from the side edges by a side trimmer to produce strip material of an exact desired width. The trimmed strip material is subjected to a leveling process after the trmming operation and then rewound in coil form for further processing. The leveling 'operation includes drawing the strip material through a leveler that includes a plurality of driven leveling rolls that force the strip material through a series of curves to thus latten all elevations and depressions in the strip material and straighten all bends prior to the coiling of the trimmed strip material. In the past, diiculty has been encountered in the leveling operation in that the tension of the strip material on the input side and output side of the leveler varied substantially and reduced the effectiveness of the leveling operation with substantial abuse to the equipment. It is the usual procedure to provide driven 'bridle or tension rolls on opposite sides of the leveler. The strip material extends around the bridle rolls, through the leveler and then around the other bridle rolls. Since the leveler also has separately driven rolls, it was found that output readings on the motors driving the bridle rolls did not give a true indication of the tension exerted on the strip material on `opposite sides of the leveler. It is highly desirable, for improved leveling technique of strip material, that the tension on the strip material on opposite sides of the leveler be maintained substantially constant.

In order to improve the leveling operation, it is an object of this invention to control the forces or tensions on the strip material passing to and delivered from the leveler.

Briefly, the invention includes a pair of spaced bridles that include guide rolls which guide the strip material to and from a leveler device. Each bridle has a guide roll mounted on suitable supports with the load cells interconnecting the supports and the guide roll. The load cells are deflected in proportion to the tension on the strip material. The load cells include a means to generate a signal proportional to the deilection. The signal from each load cell is transmitted to a common comparator. The comparator, in response to the signal generated by both of the load cells, controls the drive motor of the leveler to thereby regulate the speed of the leveler rolls and adjust the tension on the strip material so that the tension n the strip material on both sides of the leveler is substantially constant.

Accordingly, it is an object of this invention to provide a novel tension control means for a leveler device.

Another object of this invention is to provide a novel control means for maintaining constant tension on the input Aand output side of a leveler.

A further object of this invention is to provide a novel control system for the drive motor of a leveler which maintains equal tensions on the input and output side thereof.

In the drawings:

FIGURE l is a diagrammatic plan view of a leveling line where the side edges are trimmed from the strip material.

FIGURE 2 is a view in side elevation of the leveling line which is illustrated in FIGURE l.

FIGURE 3 is a schematic view of a portion of the leveling line illustrating the load cells.

FIGURE 4 is a schematic electrical diagram illustrating the manner in which the motor for the leveler is controlled by the signals transmitted by the load cells.

Referring to the drawings by numerals of reference and especially to FIGURES 1 and 2, there is illustrated a typical processing line wherein a coil of strip material generally designated by the numeral 10 is supported on an unwinding mechanism or pay-ohc reel 12. The strip material is unwound from the coil 10 and passes through a side edge trimmer 14 and a scrap cutter 16 and is then reeved around guide or dei-lector rolls i8 and 20 that are supported by a supporting mechanism 22. Motors 24 and 26 are connected to the rolls 18 and 20 to drive the same. A second pair of guide or tension rolls 28 and 30 are supported in a supporting mechanism 32 adjacent to the guide rolls 18 and 20. The strip material is reeved around the rolls 28 and 3l) as indicated in FIGURE 2. Motors 34 and 36 are suitably connected to guide rolls 28 and 30 to drive the same. The strip material is then arranged to pass through a leveler device generally indicated by the numeral 38. The leveler device 38 includes a plurality of driven leveler rolls and may be similar to the levelers manufactured and sold by Voss Engineering Company, Pittsburgh, Pennsylvania, the assignee of the instant application. The leveler rolls in leveler .38 are suitably driven by a variable speed motor 40.

After the strip material has 'been flattened or straightened by the leveler 38, it is reeved about another pair of tension rolls 42 and 44 which are suitably supported by a support device 46. Motors 48 and 50 are arranged to drive the rolls 42 and 44. Another pair of rolls 52 and 54 are suitably supported by a support device S6 adjacent to the guide rolls 42 and 44. Other motors 58 and 60 drive the guide rolls 52 and 54. The strip material iS reeved around the rolls 52 and 54 and between deilector rolls generally designated by the numeral 62. The trimmed and attened strip material is then rewound as a coil 64 for storage and further processing.

Although there is illustrated in FIGURES l and 2 a processing line where the sheet material is trimmed in addition to the leveling of the sheet, it should be understood the invention is equally applicable to any processing line that includes the leveling operation. The invention is also applicable to a processing line that includes only the leveling operation.

It is highly desirable to control the tension on the strip material between roll 28 and leveler 38 and the tension on the strip material lbetween leveler 38 and roll 44. To .maintain a constant tension on the strip material, the controls illustrated in FIGURES 3 and 4 are utilized. As shown diagrammatically in FIGURE 3, the roll 28 is mounted on a pillow block generally designated by the numeral 66. A load cell 68 is mounted on the support member 32 and operatively engages the pillow block 66. A load cell is an electrical device operative to measure `by deflection the tension on the strip material. A suitable load cell is illustrated in Design News, December 8, 1961, pages 14 and l5, in an article entitled Tensiometer Uses Bridge Mounting, Low-Deflection Load Cell, by Lars G. Soderholm. The loa-d cell is generally mounted between a bridge and a xed support so that the stress imposed on the bridge will deect the bridge and send an electrical signal to the load cell to indicate an out-ofbalance condition.

The guide roll 4 4 positioned on the opposite side of leveler 38 is also mounted on a pill-ow block 70` with a load cell 72 interconnectinng the pillow block 70 with the frame support 46. The load cells 68 and 72 are connected by means of conduits 74 and 76 to a load comparator 78. The load comparator may be any suitable device that measures the difference in outputs of the load cells 68 and 72 and is capable of providing a signal or other means indicating the difference in the load cell signals transmitted to the comparator 78. The load comparator 78 is connected by meansl of conduit 80 to a regulator device 82 that is arranged to control the speeds of leveler motor 40 through a voltage booster 84. With this arrangement any differential in signal between load cell 68 and load cell 72 is transmitted through comparator 78 to regulator 82 which either slows down or speeds up leveler 38 to control the tension on opposite sides of the leveler 38. The regulator may be controlled to provide equal tension on opposite sides of the leveler 38 or different tensions on opposite sides of the leveler. The tensions on opposite sides of the leveler 38 are cont-rolled and remain substantially constant throughout the processing of a coil of sheet material.

In operation of the apparatus illustrated in FIGURES 1 4, the motor 50 drives roll 44 at a preselected speed determined by the desired speed at which the strip material is to be .processed through the leveling line. Since the leveler 38 is independently driven by motor 40, the pull exerted on the strip material between the leveler 38 and the roll `4-2 determines the tension on the strip material -between the leveler 38 and roll 44. When the speed of leveler drive motor 40 is increased, the tension between leveler 38 and roll 44 is substantially decreased. When, however, the speed o-f the leveler drive motor 40` is increased, the pull on the strip material between the roll 28 and leveler 38 is increased. It will thus be seen that the tension indicated by 'f1-FIGURE 3-will exceed the tension T3 indicated on FIGURE 3 when the rolls in leveler 38 are being driven too fast. Also, when the leveler motor 40 drives the leveler rolls at a reduced rate, the tension T3 on the strip material between leveler 38 and roll 44 will increase substantially above tension T1. Pillow blocks 66 and 70 and load cells 68 and 72 control the tension of the strip material on opposite sides of the leveler 38. For example, if the leveler motor 40 is overdriving the rolls in leveler 38, the leveler 38 operates to pull the strip material from the roll 28 in such a manner that tension T1 exceeds tension T3. Such action deflects the pillow block 66 which registers a signal in load cell 68. This signal is transmitted through conduit 74 to comparator 78 indicating an increased tension on the strip material between roll 28 and leveler 38. The overdrive of leveler drive motor 40 will concurrently decrease tension T3 between leveler 38` and guide roll 42. Such action will deflect the pillow block 7 0 so that load cell 72 will transmit a signal through conduits 76 to comparator 78 indicating a decrease in tension of the strip material between leveler 38 and roll 42. The comparator 78 will then provide a signal for regulator 82 through conduit 80 indicating the differential in tensio-n on the opposite sides of leveler 38. The regulator 82 through voltage booster 84 will control the speed of leveler motor 40 to increase the tension between leveler 38 and guide roll 42 and decrease the tension between guide roll 30 and leveler 38, until a preselected tension is Obtained.

Conversely, if the leveler motor 40 is driving the leveler rolls at too slow a speed, the motor t) for roll 44- will increase the tension between leveler 38 and roll 44 above the tension on the strip material between roll 28 and leveler 38. The load cells 68 and 72 will transmit signals reflecting this differential in tension to the comparator 78 which, in turn, through regulator 82, will regulate the speed of leveler motor 40 until the desired condition is obtained.

It should be understood that other types of tension indicating means, comparators and motor regulator means can be utilized to practice the heretofore described i11- vention. In certain processes or with certain strip material it is desirable to controllably vary the tension exerted on the material on opposite sides of the leveler. With the invention herein taught it is possible to maintain constant tension forces on opposite sides of the leveler. These tension forces can be balancedand equal if desired or they can be controllably varied to change the tensions to any desired constant differential in tension.

According to the provisions of the patent statutes, the principle, preferred construction, and mode of operation of the invention have been explained and what is now considered to represent its best embodiment has been illustrated and described. It should be understood, however, that within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. A device for maintaining a condition of constant tension between the input side and output side of a leveler comprising a leveler device, motor means for driving said lever device, a first roll guiding a strip of material to said leveler, a second roll guiding a strip of material from said leveler, deectable supports for said first and second rolls which deflect in response to tension on said respective strips of material, means for driving said respective rolls, means responsive to the deflection of eac-h of said supports for sending a signal, and said mot-or means responsive to said signal for adjusting the speed thereof to control the tension of said strip material on the input and output side of said leveler.

2. A device for maintaining a condition of constant tension between the input and output side of a leveler comprising a leveler device for flattening strip material, motor means for driving said leveler device, a pair of spaced rolls operative to -feed strip material into and away from said leveler device, each of said rolls mounted on a pillow block supported by a frame member, means mounted on each of said frame members operatively connected to said pillow block associated therewith to detect a deflection in said pillow 4block for sending a signal to said motor means for adjusting the speed thereof to control the tensions on said strip of material passing through said leveler device.

3. A device for maintaining a condition of constant tension as set forth in claim 2 wherein said means mounted on each frame member comprises a load cell operatively connected to said motor means and responsive to deflection in said pillow blocks for sending a feedback signal to said motor means to correct for deflection in said pillo-w blocks.

`4. A device for maintaining a condition of constant tension as set forth in claim 3 wherein a comparator -operatively interconnects said load cells to said motor means to adjust the signal to said motor means from said load cells.

5. A device for maintaining a condition of constant equal tension between the input and output side of a leveler comprising a leveler device for straightening strip material fed therethrough, -a drive motor operatively connected to said leveler for feeding material introduced into said leveler, a first roll mounted on a support for feeding strip material to said leveler, a second roll mounted on a Support for feeding strip material away from said leveler, said supports being deflectable in accordance with the F tension on said respective strip materials, and means re- 0 sponslve to a difference in deection of said rst and second supports to feed back a signal to said drive motor to adjust the speed of said motor and maintain a constant balanced tension on said material between said first and second rolls.

6. A device for maintaining a condition of constant equal tension between the input and output side of a leveler as set forth in claim 5 wherein said last mentioned means comprises a load cel-l mounted on each support and responsive to a deflection by said rolls re- 5 6 spectively due to an unbalanced tension thereon to adjust References Cited by the Examiner said drive motor speed. UNITED STATES PATENTS 7. A device for maintaining a condition of constant equal tension between the input side and the output side l; Hetler 72--9 of a leveler as set forth in claim 6 wherein a comparator 5 Mccreary 72-9 interconnects said load cells to provide an outputsignal CHARLES W. LANHAM Primary Examiner. to said drlve mot-or to thereby maintain equal tension on opposite sides of said leveler. R- D- GREJFE, Examiner- 

1. A DEVICE FOR MAINTAINING A CONDITION OF CONSTANT TENSION BETWEEN THE INPUT SIDE AND OUTPUT SIDE OF A LEVELER COMPRISING A LEVELER DEVICE, MOTOR MEANS FOR DRIVING SAID LEVER DEVICE, A FIRST ROLL GUIDING A STRIP OF MATERIAL TO SAID LEVELER, A SECOND ROLL GUIDING A STRIP OF MATERIAL FROM SAID LEVELER, DEFLECTABLE SUPPORTS FOR SAID FIRST AND SECOND ROLLS WHICH DEFLECT IN RESPONSE TO TENSION ON SAID RESPECTIVE STRIPS OF MATERIAL, MEANS FOR DRIVING 